This invention relates to an oil recovery method in which oil contaminating surface waters is recovered by contacting the oil with particles of a hydrophobic macroporous highly cross-linked polymer. More particularly, the invention includes the use of small porous polymethacrylate particles as an oil adsorbent.
The concept of producing spheres and beads of a macroporous polymer is old in the art, as well as the use of such macroporous structures for the entrapment and subsequent delivery of certain active ingredients. One example of this concept may be found in U.S. Pat. No. 4,690,825 issued Sep. 1, 1987 in which a suspension polymerization process is employed to produce beads from a monomer system including styrene and divinylbenzene. Mineral oil is entrapped "in situ" and the beads are said to possess utility in various cosmetic applications. In U.S. Pat. No. 4,719,040 issued Jan. 12, 1988, a macroporous polymer laden with perfume is incorporated into an air freshener gel. U.S. Pat. No. 4,724,240 issued Feb. 9, 1988; European Patent No. 61,701 granted Jul. 16, 1986; and Canadian Patent No. 1,168,157 issued May 29, 1984, each relate to "in situ" entrapped emollients and moisturizers carried within macroporous beads. Various cosmetic and toiletry applications of these products are disclosed.
A macroporous polymer entrapping an emollient is taught in U.S. Pat. No. 4,764,362 issued Aug. 16, 1988, and in U.S. Pat. No. 4,813,976 issued Mar. 21, 1989, in which the polymer is incorporated into a nail conditioning emery board. During filing of the nails, the emollient is released in order to condition and lubricate the nails. A similar concept is taught in U.S. Pat. No. 4,776,358 issued Oct. 11, 1988 in which a dental floss includes flavor oils entrapped in certain "microsponges". Suspension polymerized macroporous polymer beads are taught in U.S. Pat. No. 4,806,360 issued Feb. 21, 1989, and in U.S. Pat. No. 4,855,144 issued Aug. 8, 1989, wherein melanin pigment is incorporated into the macroporous structure and applied to the skin and said to function as a sunscreen. Similar bead structures are also taught in European Patent Application Publication No. 306 236A2 published Mar. 3, 1989, and in Patent Cooperation Treaty International Publication No. WO 88/01164 published Feb. 25, 1988.
A reticulated polyurethane foam is disclosed in U.S. Pat. No. 4,828,542 issued May 9, 1989 having macroporous polymer particles bonded to the foam. The particles entrap a liquid soap and the foam functions as a cleaning pad. In U.S. Pat. No. 4,855,127 issued Aug. 8, 1989, and U.S. Pat. No. 4,880,617 issued Nov. 14, 1989, hydrophobic polymeric porous beads are used as a free-flowing solid carrier for various pheromones, pesticides, fragrances, and chemicals entrapped therein. Hydrophilic beads are formed in U.S. Pat. No. 4,870,145 issued Sep. 26, 1989 and upon removal of the solvent used to form the voids, the beads possess various utilities including incorporation into contact lens cleaners, facial scrubs, and tile cleaners. In U.S. Pat. No. 4,873,091 issued Oct. 10, 1989 resilient microbeads are formed by suspension polymerizing curable elastomers such as isoprene rubbers to produce porous rubber beads. The porous rubber beads are employed in topical applications. In the Patent Cooperation Treaty International Publication No. WO89/10132 published Nov. 2, 1989 porous particles are disclosed as an ingredient in personal care emulsions. A pet litter is described in U.S. Pat. No. 4,881,490 issued Nov. 21, 1989, and U.S. Pat. No. 4,883,021 issued Nov. 28, 1989, wherein a macromolecular polymer entrapping a fragrance is incorporated in an animal litter to slowly release fragrance for combating odors.
In U.S. Pat. No. 4,898,913 issued Feb. 6, 1990 macroporous hydrophobic powder materials are rendered hydrophilic by treatment of the surface of the powder. In one embodiment of the '913 patent, the surface is saponified whereas in another embodiment an acrylate monomer is polymerized on the surface. A wet wipe useful in personal care applications is disclosed in U.S. Pat. No. 4,904,524 issued Feb. 27, 1990 wherein macroporous polymeric beads containing a silicone skin conditioner are incorporated into the surface of a paper sheet. Polymeric microparticles loaded with a fungicide are taught in U.S. Pat. No. 4,923,894 issued May 8, 1990. In U.S. Pat. No. 4,933,372 issued Jun. 12, 1990 there is described rigid resin particles formed by polymerizing monounsaturated and polyunsaturated monomers within the pores of inorganic template particles such as silica gel, silica, alumina, zirconia, and metal oxides. The template particles are dissolved leaving porous adsorptive particles which mirror the template particles in size, surface area, and porosity. Macroporous particles capable of adsorbing hydrophilic as well as lipophilic fluids are taught in U.S. Pat. No. 4,948,818 issued Aug. 14, 1990.
In accordance with the present invention however a new and novel use of an otherwise old material has been discovered wherein provision is made for oil adsorption from surface waters by contact with hydrophobic macroporous polymer particles which are free of any "in situ" entrapped active ingredient. The empty macroporous particles function as a recycleable adsorbent and because of their inert nature enable the recovered oil to be reused.
Thus, in the wake of recent oil spill events involving oil tankers and other oil transporting vessels, there is a need for new and effective methods for solving such environmental problems.